The invention relates to a switching device comprising a substrate and a thin switching film containing a metal compound. The invention also relates to applications of such a switching device.
In the relevant switching devices, the electrical and/or optical properties are governed by external influences, such as mechanical stress or electric voltage, gas pressure, relative humidity, concentration etc.
For example, electrochromic devices are well-known, in which a layer of an electrochromic material, such as MoO.sub.3, is sandwiched between two transparent electroconductive electrode layers, for example, of indium-tin oxide. A layer of an H.sup.+ - or Li.sup.+ -ion-conducting material is present between an electrode and the electrochromic material. The device often also comprises a counter electrode for storing ions. The application of the electric potential of several volts across the electrodes causes the transmission of the layer packet to change. Said transmission change is reversal. Electrochromic materials are used, for example, in variable-transmission windows for buildings and anti-dazzle mirrors in cars.
A drawback of oxidic electrochromic devices is that an extensive layer stack is required for their operation. A further important disadvantage is that such materials enable only a small transmission change, and hence a small contrast, to be attained.